The article proposes a methodological approach to the quantitative assessment of direct economic damage from natural hazards for an element of the critical infrastructure of the Russian Federation – railways. The methodology is based on a normative approach to assessing the replacement cost of railway lines, which varies depending on the cost of construction in specific orographic and climatic conditions of a given region. The results are presented in the context of municipalities, which makes it easier to take into account intra-regional differences and to compare them with natural hazard parameters (e.g. floods, dangerous slopes, geocryological processes, etc.). The calculations showed that the marginal cost of replacing railway lines in the event of natural hazards for Russia is about RUB 11 trillion in 2021 prices, or about 8.4% of Russia’s GDP for that year. In a regional context, the first 10 regions account for more than 40% of the total replacement cost, which indicates that these regions require special attention in terms of measures to protect railway assets. These include Irkutsk oblast (RUB 602.4 bln), Khabarovsk krai (595.5), Amur oblast (594.4), Zabaykalsky krai (538.2), Sverdlovsk oblast (526.8), Krasnoyarsk krai (406.8), Altai krai (404.3), Krasnodar krai (348.5), Republic of Buryatia (314.1), Primorsky krai (287.7). The data obtained can be used in studies of natural and man-made risks: by comparing them with the parameters characterising the impact of natural hazards, it is possible to predict the risk and probable damage to railway infrastructure facilities in the given territories. Avalanches and permafrost degradation are used to demonstrate the potential of such assessments.

The requirements for the calculation of indicators of avalanche activity determined by climatic conditions in the territories under developing, as well as prognosis of their changes in the future are enshrined in Russian Federation legislation. However, the data required for this do not exist for all the regions of the country, especially those, that are only now included in the industrial exploration. The dependences between the climatic and the geomorpho- logical indicators and parameters of avalanches and avalanche activity are developed earlier on the basis of data from direct observations. The indicators are based on the average annual maximum ten-day snow cover height, the number of days with snow cover, the duration of the avalanche period and the average long-term frequency of avalanches. The climatic parameters presented by model MRI-CGCM3 (RCP 8.5) were incorporated into these dependences system. This made possible to estimate the indicators of avalanche activity for the middle and for the end of the 21st century. Also, their changes relative to the present conditions were assessed. Thus, a methodology was successfully tested that allows to include normatively defined characteristics of avalanche activity in the anal- ysis and forecasts of regional climate changes for any climate scenarios.

For the first time, a qualitative and quantitative evaluation of the effectiveness of anti-avalanche measures was carried out for the territory of the «Krasnaya Polyana» ski resort, located in the Western Caucasus on the Aibga ridge. The following materials were used for this work: the results of field survey in 2019, which made it possible to map the resort's infrastructure exposed to possible snow avalanches and protected by existing preventive (anti-avalanche) measures, experience of similar studies from other regions as well as identification of the avalanche release zones by means of digital elevation model and analysis of remote sensing data, archive data on the snow avalanches regime at the site, and numerical modeling of the snow avalanches with different starting conditions. Modeling of the avalanches was performed in the RAMMS program basing on three scenarios: 1) taking account of the successful operation of existing anti-avalanche measures; 2) with regard for the failures in the work of existing anti-avalanche measures that were recorded earlier during the operation of the resort; 3) without considering any anti-avalanche measures, which corresponded to the conditions at the stage of the territorial planning of the resort. Differences in the impact of simulated avalanches on the resort infrastructure were interpreted as «high», «medium» and «low» effectiveness of existing antiavalanche measures. It was found that the dynamical characteristics of the local avalanches (run-out distance, volume, velocity, and pressure) had different importance for different types of the infrastructure with regard to the effectiveness of anti-avalanche measures. Under existing conditions of the relief, climate and vegetation of the investigated territory the artificial triggering (at the ski resort it is mainly made by the Gazex systems) is the most efficient. Snow-retaining structures often do not perform their functions, while dams and avalanche cutters can be successful only in combination with the properly functioning artificial triggering. It was found that there are areas where the run-out distance of artificially controlled avalanches is smaller than that of possible natural avalanches, and these areas can still be dangerous for the infrastructure of the resort due to the high values of the avalanche speed and pressure.

For the first time, a qualitative and quantitative evaluation of the effectiveness of anti-avalanche measures was carried out for the territory of the "Krasnaya Polyana" ski resort, located in the Western Caucasus on the Aibga ridge. The following materials were used for this work: the results of field survey in 2019, which made it possible to map the resort's infrastructure exposed to possible snow avalanches and protected by existing preventive (anti-avalanche) measures, experience of similar studies from other regions as well as identification of the avalanche release zones by means of digital elevation model and analysis of remote sensing data, archive data on the snow avalanches regime at the site, and numerical modeling of the snow avalanches with different starting conditions. Modeling of the avalanches was performed in the RAMMS program basing on three scenarios: 1) taking account of the successful operation of existing anti-avalanche measures; 2) with regard for the failures in the work of existing anti-avalanche measures that were recorded earlier during the operation of the resort; 3) without considering any anti-avalanche measures, which corresponded to the conditions at the stage of the territorial planning of the resort. Differences in the impact of simulated avalanches on the resort infrastructure were interpreted as "high", "medium" and "low" effectiveness of existing anti-avalanche measures. It was found that the dynamical characteristics of the local avalanches (run-out distance, volume, velocity, and pressure) had different importance for different types of the infrastructure with regard to the effectiveness of anti-avalanche measures. Under existing conditions of the relief, climate and vegetation of the investigated territory the artificial triggering (at the ski resort it is mainly made by the Gazex systems) is the most efficient. Snow-retaining structures often do not perform their functions, while dams and avalanche cutters can be successful only in combination with the properly functioning artificial triggering. It was found that there are areas where the run-out distance of artificially controlled avalanches is smaller than that of possible natural avalanches, and these areas can still be dangerous for the infrastructure of the resort due to the high values of the avalanche speed and pressure.

The legislation of the Russian Federation establishes the need to take into account hazardous natural processes and their parameters in territorial planning, as well as presentation of them in the relevant documentation in the form of maps. In a number of countries, there is a long-standing practice of mapping the avalanche zones basing on the definition of different levels of danger, which are used to limit or ban the construction in avalanche zones, as well as to project the anti-avalanche activities. Russia has experience in assessing risk and mapping the avalanche danger, but the practice of making such plans in our country is still not developed. The purpose of this work is to determine and plot on map avalanche zones on the example of one of the actively developed mountain regions of Russia. The all-season mountain resort «Gorky Gorod», located on Krasnaya Polyana in the Krasnodar region, was chosen as the object of study. Two approaches to the accounting and mapping of avalanche hazard in territorial planning were tested. In the first case, occurrence and pressure of avalanches were the determining factors. In the second case, critical avalanche pressure values were used to determine their destructive impact effect. To determine indexes (indicators) of the avalanche hazard, the simulation of snow avalanches in the RAMMS program was performed. According to the results of modeling for area of the «Gorky Gorod» resort schemes of the avalanche zones were constructed on the basis of two different approaches, having no account for the anti-avalanche measures used there. A more detailed plan based on a combination of these two approaches had also been drawn up and analyzed. The required criteria for determining the boundaries of zones with different levels of the danger are the subject for discussion. However, the proposed division of avalanchedangerous territory into zones with different levels of the hazard at the stage of territorial planning meets the requirements of the legislation and contributes to improving human security, reducing the avalanche risk, and mitigating the consequences of emergencies caused by avalanches.

The contribution of snow avalanches to the seasonal snow accumulation on a glacier is among the least studied components of the glacier’s mass balance. The methods for the numerical assessment of avalanche accumulation are still under development, which is related to poor avalanche data availability and difficulties in obtaining such data on most of mountain glaciers. We propose a possible methodology for the numerical assessment of snow avalanche contribution to snow accumulation at mountain glaciers based on DEM and weather data analysis using GIS and numerical modeling of snow avalanches. The developed methodology consists of the following steps: terrain analysis; weather data analysis; snow avalanche volume assessment during an analyzed balance year; numerical simulation of snow avalanches using RAMMS; evaluation of snow avalanches contribution into a glacier accumulation. The proposed methodology was tested on three glaciers located in the Inner Tien Shan: Batysh Sook, № 354 and Karabatkak during the 2015/16 balance year. To evaluate snow avalanche contribution to the seasonal accumulation, we reconstructed avalanche release zones that were most probably active during the 2015/16 balance year and corresponding snow fracture height in each of these zones. The numerical simulations of most probable released snow avalanches during the winter period 2015/16 using avalanche dynamics software RAMMS were performed and compared with the field observations and UAV orthophoto image from July 2016. The outlines of avalanches deposits were realistically reproduced by RAMMS according to the results of field observation. The estimated share of snow avalanche contribution to the accumulation on the research glaciers during the 2015/16 balance year turned out to be: Batysh Sook – 7,4±2,5%; № 354 – 2,2±0,7%; Karabatkak – 10,8±3,6% of the total accumulation. The next step would be to test the proposed methodology based on the data and regional dependences from the Inner Tien Shan in other mountainous regions. This methodology is applicable in the regions where DEMs, regular meteorological observations as well as data on the regional avalanche formation factors are available.